We have reported that DNA from human leukemia cells can be transfected into mouse splenic lymphocytes to produce continuous cell lines. The work is now focuses on the characterization of these lymphocyte "transfectants" and the mechanism by which the incorporation of the human "oncogenic DNA" induces continued proliferation. We are attempting to: (1)\define the oncogene(s) from the leukemia cells which activate the lymphocytes to proliferate; (2)\determine if a second oncogene can take the transfected lymphocytes another step toward being fully "transformed" tumor cells; (3)\use the lymphocyte and NIH/3T3 transfection systems to determine whether certain cloned oncogene constructions can transform one cell type more effectively than another; and (4)\determine what other alterations in gene expression take place as a result of the transfection with the "oncogenic" DNA. (M)